Properly implemented visualization._get_num_rows() and added unit tests

sw/test/test_visualization.py

@@ -0,0 +1,24 @@
+import unittest
+from utility import visualization
+
+
+class NumRowsTestCase(unittest.TestCase):
+    def test_get_num_rows(self):
+        """Test case for number of row calculation."""
+
+        num_rows1 = visualization._get_num_rows(4, 2)
+        expected_rows1 = 2
+
+        num_rows2 = visualization._get_num_rows(5, 2)
+        expected_rows2 = 3
+
+        num_rows3 = visualization._get_num_rows(4, 4)
+        expected_rows3 = 1
+
+        num_rows4 = visualization._get_num_rows(4, 5)
+        expected_rows4 = 1
+
+        self.assertEqual(num_rows1, expected_rows1)
+        self.assertEqual(num_rows2, expected_rows2)
+        self.assertEqual(num_rows3, expected_rows3)
+        self.assertEqual(num_rows4, expected_rows4)